The advent of geographic online social networks such as Foursquare, where users voluntarily signal their current location, opens the door to powerful studies on human movement. In particular the fine granularity of the location data, with GPS accuracy down to 10 meters, and the worldwide scale of Foursquare adoption are unprecedented. In this paper we study urban mobility patterns of people in several metropolitan cities around the globe by analyzing a large set of Foursquare users. Surprisingly, while there are variations in human movement in different cities, our analysis shows that those are predominantly due to different distributions of places across different urban environments. Moreover, a universal law for human mobility is identified, which isolates as a key component the rank-distance, factoring in the number of places between origin and destination, rather than pure physical distance, as considered in some previous works. Building on our findings, we also show how a rank-based movement model accurately captures real human movements in different cities.
Vegetation and moisture play the most important roles in controlling daytime urban heat islands and their spatial variability. More than half of the world’s population now live in cities, which are known to be heat islands. While daytime urban heat islands (UHIs) are traditionally thought to be the consequence of less evaporative cooling in cities, recent work sparks new debate, showing that geographic variations of daytime UHI intensity were largely explained by variations in the efficiency with which urban and rural areas convect heat from the land surface to the lower atmosphere. Here, we reconcile this debate by demonstrating that the difference between the recent finding and the traditional paradigm can be explained by the difference in the attribution methods. Using a new attribution method, we find that spatial variations of daytime UHI intensity are more controlled by variations in the capacity of urban and rural areas to evaporate water, suggesting that strategies enhancing the evaporation capability such as green infrastructure are effective ways to mitigate urban heat.
Abstract Transverse cracking is a major distress mechanism in Continuously Reinforced Concrete Pavement (CRCP), affecting ride smoothness, service life, and maintenance strategies. This research introduces a hybrid predictive framework that couples Particle Swarm Optimization (PSO) with Gradient Boosting Machine (GBM) to enhance the accuracy of transverse crack prediction in CRCP. The analysis utilized 395 records from 33 pavement sections obtained from the Long-Term Pavement Performance (LTPP) program, encompassing structural, environmental, traffic, and performance-related parameters. PSO was applied to fine-tune critical GBM hyperparameters, namely the number of iterations, learning rate, and tree depth. The optimized PSO–GBM model demonstrated excellent performance, yielding an average RMSE of 1.62 and an R2 of 0.99 under 5-fold cross-validation, surpassing benchmark models such as conventional GBM, Random Forest, Support Vector Regression (SVR), Artificial Neural Networks (ANN), and Linear Regression. Sensitivity analysis revealed that L3 thickness, L4 thickness, and Annual Average Daily Traffic (AADT) were the most significant contributors, consistent with engineering knowledge of crack development. Validation through residual distribution and equality line plots confirmed the robustness and stability of the proposed approach across varying severity levels.
Abstract Setback regulations, a fundamental component of urban planning and development control, are frequently overlooked in Bangladesh, thereby compromising the principles of urban sustainability. This study examines the critical role of setbacks in ensuring adequate solar access within the Nirala Residential Area—a formally planned neighbourhood in Khulna City. Utilising ArcGIS 3D analysis tools, the research quantified structure shadow volumes during the summer and winter seasons of 2023. The study explored the impact of incremental increases in setback distances beyond current regulatory standards on solar access. Shadow volumes were assessed at distinct intervals—3.00 pm, 3.15 pm, and 3.30 pm during summer, and 2.00 pm, 2.15 pm, and 2.30 pm in winter—to evaluate temporal and seasonal variations. The findings indicate a clear seasonal dependency in sunlight accessibility, significantly influenced by setback dimensions. Specifically, a 15% augmentation to existing setback standards emerged as the most effective, yielding reduced shadowing in winter and enhanced shading during the hotter summer months. This research provides valuable insights for urban policymakers and planners, underscoring the potential of setback regulations in fostering sustainable urban environments. By advocating for revised and more context-sensitive setback guidelines, the study promotes improved living conditions, public health, and environmental quality through greater access to natural light and the creation of climate-responsive neighbourhoods.
Cities. Urban geography, Urban groups. The city. Urban sociology
Social media platforms provide a real-time lens into public sentiment during natural disasters; however, models built solely on textual data often reinforce urban-centric biases and overlook underrepresented communities. This paper introduces an adaptive cross-city learning framework that enhances disaster sentiment understanding by integrating mobility-informed behavioral signals and city similarity-based data augmentation. Focusing on the January 2025 Southern California wildfires, our model achieves state-of-the-art performance and reveals geographically diverse sentiment patterns, particularly in areas experiencing overlapping fire exposure or delayed emergency responses. We further identify positive correlations between emotional expressions and real-world mobility shifts, underscoring the value of combining behavioral and textual features. Through extensive experiments, we demonstrate that multimodal fusion and city-aware training significantly improve both accuracy and fairness. Collectively, these findings highlight the importance of context-sensitive sentiment modeling and provide actionable insights toward developing more inclusive and equitable disaster response systems.
Abstract As for the academics and policymakers, more attention has been given to the issue on how to drive urban innovation through the cooperation of environmental regulation and FDI. With the use of a city-level panel data of 285 Chinese cities from 2003 to 2017, this study preliminary explores the impacts of environmental regulation, FDI, and its interaction term on urban innovation at national and regional levels. Specifically, based on the spatial Durbin model under the space-and-time fixed effect, three different spatial weight matrixes (i.e. the first-order adjacency, the inverse distance, and the economic distance) are utilized to check the robustness of the results under different standards. The results indicate that the impacts of FDI and environmental regulation on urban innovation have not achieved the desired goal without the other's cooperation, while most of its interaction term's coefficients on urban innovation are significantly positive, which provides robust support for the establishment of “Porter hypothesis” in China. Moreover, spatial heterogeneity is established, and the uneven development of urban innovation among different regions deserves more attention. In order to effectively increase the ability of urban innovation in China, the government should focus on such solutions as enhancing the implementation and supervision efficiency of environmental regulation, optimizing the structure of FDI, improving the synergistic effects of environmental regulation and FDI, and establishing a multi-scale spatial cooperation mechanism based on both geographical and economic correlations.
Abstract The Urban Heat Island concept is often used to describe ‘excess’ heat associated with urban areas, and is therefore frequently considered to be a negative phenomenon that requires mitigation. In this short communication we use clear examples to show that this is not necessarily true. Furthermore, we demonstrate that the Urban Heat Island intensity has little relevance for urban heat mitigation, and suggest the term “urban heat mitigation” to more accurately describe strategies aimed at cooling cities. We conclude with the research questions that, in our view, should guide future studies in the fields of urban thermal climate and heat mitigation. These questions are primarily rooted in the assessment of differences of climate responses between built Local Climate Zones in different climatic and geographical contexts.
Abstract With urban densification and the proliferation of high-rise structures, residents’ apartment views are getting obstructed from surrounding nature, especially greenery. Existing approaches often rely on simplified proxies or aggregated building- or floor-level metrics which does not capture individual-level variation. Most of them use coarse spatial data or subjective self-reports, lacking the granularity and precision to quantify the greenery visible to each resident from their own living space. This study introduces a conceptual and methodological framework for objectively modelling green views at the individual apartment level. Our Apartment Greenery View Measure was developed and assessed by (1) geocoding individual observer positions at window-level within apartment buildings, (2) implementing GIS-based three-dimensional viewshed analysis using high-resolution environmental datasets to objectively quantify views, and (3) examining agreement between modelled views and 445 residents’ self-reported perceptions using the green-to-grey ratio. The method was applied to 30 apartment buildings across Melbourne, Australia. Findings reveal variability in green view exposure by building height, floor-level, and apartment orientation. A moderate correlation (r = 0.556, ICC = 0.521) shows the agreement between objective and perceived view measures, with 39.1% participants overestimating and 60.9% underestimating their views. This underscores the need for objective, standardised measures that move beyond perception alone. The workflow supports aggregation at multiple spatial scales, from individual units to floors and buildings, providing a flexible framework for assessing visual green equity citywide. This provides a scalable, low-cost tool for planners, designers, and health researchers seeking to integrate visual greenery into urban housing, policy, and equity-focused interventions.
Introduction The environmental impact of mega-events like the Olympic Games and the FIFA Men's World Cup has been widely criticized due to their significant contribution to greenhouse gas emissions, largely driven by infrastructure construction and resource use, and travel. Despite sustainability initiatives introduced by the IOC since the 1990s, including the 2017 "Sustainability Strategy," research indicates that these efforts rarely lead to tangible results, with environmental scores of the Games declining over time (Müller et al., 2021). Policies such as Agenda 2020 are mostly seen as recommendations, not obligations, contributing to accusations of greenwashing and unmet environmental commitments. The lack of a standardized framework for assessing and mitigating environmental impacts highlights the gap between promises and outcomes, suggesting that current approaches are insufficient to align mega-events with sustainability goals (Collins et al., 2009; Gaffney, 2013). This research thesis examines this gap to understand the ineffectiveness of these policies and their evolution over time using the policy mobility methodology, which allows us to understand how policies are created, transferred and reapplied in a new context, thanks to tools and people who transport knowledge from one place to another. The research highlights the evolution of environmental policy in the Olympic Games, tracing its origins from global environmental movements to its integration within the framework of the International Olympic Committee.
Methods The methods used in this research focus on understanding the challenges of policy mobility and sustainability in the context of the Olympic Games. Policy mobility is a concept that analyzes how policies, conceived locally, circulate, adapt and apply in new contexts, particularly in a globalized. Unlike traditional nation-state-centric approaches, policy mobility emphasizes the role of non-state actors, international networks of experts, and global organizations in policy diffusion and transformation (Cochrane & Ward, 2012). In the context of mega-events such as the Olympic Games, it explains how sustainability-related practices and ideas travel between editions of the Games, influencing local policies while being reconfigured according to specific contexts. The study employs text-based methods, such as content and discourse analysis of policy documents and official IOC publications, as well as oral methods through interviews with key actors involved in the organization of the Games. This dual approach allows for an in-depth analysis of how policy ideas travel, the role of individuals in this process, the materials used for policy travel, and the politics of policy mobility (Temenos & Ward, 2018). The text-based analysis is built on a database [DG1] of the Olympic Games' carbon footprint using M. Müller's methodology, which emphasizes longitudinal and systematic data collection to identify sustainability patterns in mega-events (Gogishvili et al., 2024; Müller et al., 2022). This allowed for the analysis of all documents related to Paris 2024's sustainability policy, including its sustainability commitments, sustainability and legacy plan, two pre-games sustainability reports, and the final sustainability report.
Results Despite initiatives such as Agenda 21, Olympic Agenda 2020 and Agenda 2020+5, which aim to embed sustainability into the Games, their impact remains uneven. While the IOC encourages the introduction of sustainable practices since from the planning phases of the Games since 2003 and has introduced carbon management plans and sustainability reporting requirements, its reliance on recommendations rather than enforceable commitments limits their effectiveness. The analysis revealed that policy mobility plays a crucial role in shaping sustainability policies for the Olympic Games, as host cities adapt approaches from previous editions. This exchange, facilitated by the IOC's Olympic Games Knowledge Management program and informal expert networks, allows cities to implement proven strategies, such as carbon management plans and infrastructure reuse. However, the effectiveness of these policies is often hampered by the performative nature of environmental commitments, with actual results falling short of stated ambitions, as evidenced by the Paris 2024 case study. While the organizers aimed to halve the Games' carbon footprint and achieve a "positive climate impact", key measures, such as the AMO (Avoid, Mitigate, Offset) approach, lack clear methodologies and actionable details. For instance, despite promises to systematically assess environmental impacts at all venues, no methodology was provided for some key sites like Tahiti, highlighting gaps between goals and execution. These findings highlight the tension between the sustainability goals of the Olympic Games and the practical challenges of implementation despite the popularity of some of these policies among host cities.
Discussion/Conclusion While the IOC has made strides in integrating sustainability into its strategic goals, such as through the adoption of the Olympic Agenda 2020 and its Sustainability Strategy, the practical impact of these initiatives remains limited. The absence of standardized metrics for assessing and comparing environmental performance across editions of the Games makes it difficult to evaluate progress or enforce accountability. Weak accountability frameworks, such as voluntary reporting requirements and non-mandatory guidelines, leave much of the responsibility to Organizing Committees. Additionally, policy mobility does not always produce policies tailored to the unique challenges and opportunities of each host city. While the theory aims to create quantifiable and comparable outcomes, differences in economic, political, and cultural contexts often hinder adaptability. These variations in starting points make it difficult to implement standardized policies effectively across diverse host cities.
References
Cochrane, A., & Ward, K. (2012). Researching the geographies of policy mobility: Confronting the methodological challenges. Environment and Planning A: Economy and Space, 44(1), 5–12. https://doi.org/10.1068/a44176
Collins, A., Jones, C., & Munday, M. (2009). Assessing the environmental impacts of mega sporting events: Two options? Tourism Management, 30(6), 828–837. https://doi.org/10.1016/j.tourman.2008.12.006
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A longstanding puzzle in urban science is whether there's an intrinsic match between human populations and the mass of their built environments. Previous findings have revealed various urban properties scaling nonlinearly with population, yet existing models of city built mass are still dominated by per-capita linear thinking. Our analysis of >3,000 cities globally reveals universal sublinear scaling of city mass with population at both the city (\{beta}=0.90) and neighborhood levels (δ=0.75). This means that larger cities and denser neighborhoods achieve economies of scale with less per-capita built mass. Our theoretical framework further shows that city-level scaling emerges naturally from within-city disparities. This multi-scale understanding redefines "over-built" and "under-built" conditions as deviations from expected scaling patterns, implying either excessive environmental impacts or inadequate living standards. Effective urban policy thus requires moving beyond simple per-capita assumptions, adopting scale-adjusted metrics and managing cities as nested, complex systems.
Human mobility, a pivotal aspect of urban dynamics, displays a profound and multifaceted relationship with urban sustainability. Despite considerable efforts analyzing mobility patterns over decades, the ranking dynamics of urban mobility has received limited attention. This study aims to contribute to the field by investigating changes in rank and size of hourly inflows to various locations across 60 Chinese cities throughout the day. We find that the rank-size distribution of hourly inflows over the course of the day is stable across cities. To uncover the microdynamics beneath the stable aggregate distribution amidst shifting location inflows, we analyzed consecutive-hour inflow size and ranking variations. Our findings reveal a dichotomy: locations with higher daily average inflow display a clear monotonic trend, with more pronounced increases or decreases in consecutive-hour inflow. In contrast, ranking variations exhibit a non-monotonic pattern, distinguished by the stability of not only the top and bottom rankings but also those in moderately-inflowed locations. Finally, we compare ranking dynamics across cities using a ranking metric, the rank turnover. The results advance our understanding of urban mobility dynamics, providing a basis for applications in urban planning and traffic engineering.
In cities across the world, animals reflect, reproduce and transform urban inequalities – yet their role in mediating social hierarchies remains undertheorized. Urban scholars have begun to highlight the importance of infrastructures and technologies in configuring access to essential goods and services. While this research provides key insights into how non-human entities mediate unequal relations, it has largely overlooked how certain animals – „political animals“ – also co-produce inequalities. This article focuses on two critical urban domains, security and public health, that are often characterized by stark inequalities, and takes the role of key animals within these domains – dogs and rats, respectively – as a new analytical entry-point. Security dogs are socialized to identify threatening individuals on the basis of classed and raced markers. Rats thrive in upscale neighborhoods with historical architecture and abundant green space – yet the public health risks and the stigma associated with these rodents may disproportionately affect low-income residents. Drawing on research on security dogs in Kingston, Jamaica and rats in Amsterdam, this talk discusses the role of animals in the formation of sociospatial boundaries, and the distribution of resources and risks across urban spaces and populations. Focusing on the interactions these two types of „political animals“ have with both humans and infrastructure, it sets out a research agenda for studying how animals’ everyday encounters with their cultural and material environments combine to result in (in-)equitable social outcomes.
Cities. Urban geography, Urban groups. The city. Urban sociology
With the rise of geospatial big data, new narratives of cities based on spatial networks and flows have replaced the traditional focus on locations. While plenty of research have empirically analyzed network structures, there lacks a state-of-the-art synthesis of applicable insights and methods of spatial networks in the planning context. In this chapter, we reviewed the theories, concepts, methods, and applications of spatial network analysis in cities and their insights for planners from four areas of concern: spatial structures, urban infrastructure optimizations, indications of economic wealth, social capital, and residential mobility, and public health control (especially COVID-19). We also outlined four challenges that planners face when taking the planning knowledge from spatial networks to actions: data openness and privacy, linkage to direct policy implications, lack of civic engagement, and the difficulty to visualize and integrate with GIS. Finally, we envisioned how spatial networks can be integrated into a collaborative planning framework.
Street view imagery (SVI) has been instrumental in many studies in the past decade to understand and characterize street features and the built environment. Researchers across a variety of domains, such as transportation, health, architecture, human perception, and infrastructure have employed different methods to analyze SVI. However, these applications and image-processing procedures have not been standardized, and solutions have been implemented in isolation, often making it difficult for others to reproduce existing work and carry out new research. Using SVI for research requires multiple technical steps: accessing APIs for scalable data collection, preprocessing images to standardize formats, implementing computer vision models for feature extraction, and conducting spatial analysis. These technical requirements create barriers for researchers in urban studies, particularly those without extensive programming experience. We developed ZenSVI, a free and open-source Python package that integrates and implements the entire process of SVI analysis, supporting a wide range of use cases. Its end-to-end pipeline includes downloading SVI from multiple platforms (e.g., Mapillary and KartaView) efficiently, analyzing metadata of SVI, applying computer vision models to extract target features, transforming SVI into different projections (e.g., fish-eye and perspective) and different formats (e.g., depth map and point cloud), visualizing analyses with maps and plots, and exporting outputs to other software tools. We demonstrated its use in Singapore through a case study of data quality assessment and clustering analysis in a streamlined manner. Our software improves the transparency, reproducibility, and scalability of research relying on SVI and supports researchers in conducting urban analyses efficiently. Its modular design facilitates extensions of the package for new use cases.
In a recent note F. Lin showed that if a rational homology sphere $Y$ admits a taut foliation then the Heegaard Floer module $HF^-(Y)$ contains a copy of $\mathbf{F}[U]/U$ as a summand (arXiv:2309.01222). This implies that either the $L$-space conjecture is false or that Heegaard Floer homology satisfies a geography restriction. We verify that Lin's geography restriction holds for a wide class of rational homology spheres. Indeed, we show that the Heegaard Floer module $HF^-(Y)$ may satisfy a stronger geography restriction.